1. Field of the Invention
The present invention relates to an air conditioner.
2. Description of Related Art
A conventional air conditioner is disclosed in JP-A-H6-2886. The air conditioner is a one-unit type in which an indoor portion that is placed indoors is placed at the front, and an outdoor portion that is placed outdoors is placed at the back. The indoor portion and the outdoor portion are adjacent to each other via a partition wall. In the outdoor portion, a compressor that operates the refrigerating cycle is disposed. At the back of the outdoor portion, an outdoor heat exchanger connected to the compressor is disposed, and facing the outdoor heat exchanger, an outdoor fan for cooling the outdoor heat exchanger is provided.
At the front of the indoor portion, an air inlet is provided, and above the air inlet, an air outlet is provided. In the indoor portion, an air passage is formed by an air duct connecting the air inlet and the air outlet, and in the air passage, a blower fan is provided. Between the blower fan and the air inlet, an indoor heat exchanger connected to the compressor via a refrigerant pipe is disposed. Between the blower fan and the indoor heat exchanger, a heater unit having a plurality of tubular heaters is disposed.
When cooling operation starts, the compressor is driven to operate the refrigerating cycle, with the indoor heat exchanger serving as a cold-side evaporator of the refrigerating cycle, and the outdoor heat exchanger as a hot-side condenser. The outdoor heat exchanger is cooled by the outdoor fan to dissipate heat. As the blower fan is driven, the air inside the room flows through the air inlet into the air passage, and the air has its temperature lowered by heat exchange with the indoor heat exchanger, and is then blown into the room through the air outlet. In this way, the room is cooled.
When heating operation starts, the compressor is driven to operate the refrigerating cycle, with the indoor heat exchanger serving as the hot-side condenser of the refrigerating cycle and the outdoor heat exchanger as the cold-side evaporator. The temperature of the outdoor heat exchanger is raised by the outdoor fan. As the blower fan is driven, the air inside the room flows through the air inlet into the air passage, and has its temperature raised by heat exchange with the indoor heat exchanger. Moreover, the heater is driven to further raise the temperature of the air in the air passage. The air, having had its temperature raised, is blown out through the air outlet into the room to heat the room.
In a left part of the partition wall, a ventilation damper for introducing outside air into the room is provided in an openable/closable manner; in the rear surface of the air duct, an opening is provided. When the ventilation damper is opened while the blower fan is being driven, outside air flows through the ventilation damper, via the opening, into the air passage. The outside air having flowed in through the opening flows through the air passage and blows out through the air outlet. In this way, the room is ventilated.
According to the conventional air conditioner described above, however, the heater unit is a single unit having a plurality of heaters held by a resin-molded holder, and is fitted inside the casing of the indoor portion with the holder screwed to the casing. Here, the holder makes contact with the heaters, and thus needs to be heat-resistant (for example, 260° C. or above) and flame-retardant (for example, UL standard 94 rating 5V). Thus, as the material of the holder, expensive resin such as PPS (polyphenylene sulfide) resin is used, which disadvantageously increases the cost of the air conditioner.
Moreover, according to the conventional air conditioner described above, the heater unit is disposed in a position overlapping the blower fan as seen from above, and is fastened in the air passage with screws from the front. After the heater unit is fitted, the indoor heat exchanger is fitted at the front. Thus, when there is a failure with the heater, the indoor heat exchanger connected to the refrigerant pipe needs to be moved away so that the heater unit can be detached/attached from the front for replacement. This disadvantageously makes replacement of the heater unit troublesome and makes maintenance difficult.
Moreover, according to the conventional air conditioner described above, the ventilation duct is arranged lopsidedly toward the left; thus, while ventilating, the amount of outside air flowing into the air passage is larger near the ventilation duct than away from it. This disadvantageously causes the amount of air flowing through the air passage to be uneven between the left and right parts thereof.